Vacuum tanks having an interior pressure below atmospheric pressure are used to suction or draw material such as fluids, fluid slurries or sludges into the vacuum tank for storage. These vacuum tanks may be used as standalone tanks but such vacuum tanks may also be mounted on the cargo bed of a truck or trailer. Clear or transparent sight glass tubes made of a heavy safety glass or a polymer hose material are often mounted on the vacuum tanks so a user may readily determine by visual inspection the level of contents fluids being retained in the tank. One problem associated with such sight glass tubes is that the interior surfaces of the tubes often become coated with dirt, oil, or other contaminating coatings so a visual determination of the fluid level in the tank becomes difficult if not impossible. In order for the glass tube to be cleaned, it must typically be removed from the tank and then scrubbed or water hosed to remove the interior surface coatings so the sight glass is suitable for use. Then the sight glass tube must be reattached to the tank. Depending upon the placement of the flanges and valves used for mounting the sight glass tube to the tank, such removal, cleaning and reattachment is often inconvenient and time consuming.
A need exists for an apparatus to allow the sight glass tube to be readily cleaned without having to remove the sight glass tube from the vacuum tank.